1. Field of the Invention
This invention relates generally to the sampling of coal and similar materials, and particularly to the sampling of coal delivered by truck or other open conveyance for subsequent analysis to determine the quality of the coal.
2. Description of the Prior Art
Many coal consumers, particularly coal fired power generating plants, are receiving coal via trucks. The received coal is deposited into storage piles where it is not easily sampled for Btu's, sulfur, and other characteristics. The coal is usually received directly from a mine, and therefore the size of the coal and vary from large lumps to fines. There is no way known of adequately sampling truck received direct-from-mine coal.
More specifically, much of the coal which is received in such open trucks at power plants, and the like, is what is known as Run-of-Mine, generally abbreviated "ROM", coal. This coal is basically the product of a mine, which product has not been washed, prepared, screened, crushed, or sized. Coal received by a utility, for example, can be "ROM", or can be totally prepared, or can be sized, or any combination of these states depending upon economics and the burning characteristics of the coal. Nevertheless, since a substantial amount of the coal received is "ROM", there is a definite need for a sampler which has the capability of sampling such coal, and especially large size coal, and which is not limited to only a small sized coal sampling procedure.
The main and only goal in sampling is to obtain an unbiased sample from a given quantity of material that is accepted as a representative sample to both the seller and the buyer. This is best accomplished by extracting a true vertical core from the truck bed, rail car, or barge, when other methods of sampling are not applicable.
U.S. Pat. No. 3,158,030, issued Nov. 24, 1964 to G. B. Cross, discloses a mechanical coal sampler which employs a vertically disposed tube for reciprocal movement on a horizontally extending carriage in order to obtain a sample from a coal-laden truck and transferring the sample to a conveyor system for processing. This known sampler is typical of the prior art devices which only work satisfactorily on small sized lump product; in particular, lumps or pieces of material no larger than the size of the sampling tube. Further, U.S. Pat. No. 3,447,381, issued June 3, 1969 to R. W. Langtry et al, discloses a sampling mechanism which employs an auger, while U.S. Pat. No. 2,738,679, issued Mar. 20, 1967 to W. T. Senkowski, discloses a solid sampling apparatus which returns a discarded portion of a sample to the flow of product being sampled. The augers disclosed in U.S. Pat. No. 3,447,481, however, must dig through the coal bed, and in the process will take a path of least resistance which will not represent a true vertical core and will produce probable bias, since the only driving force downward is the weight of the device itself. U.S. Pat. No. 2,738,679, discloses a sampler only applicable to a moving stream of material, such as the discharge from the discharge pulley of a conveyor belt. It returns a portion of the primary sample not retained to a main stream of the material, but this prior device is not applicable to the sampling of material from a stationary quantity thereof disposed in an open container such as a truck bed, rail car, or barge.
U.S. Pat. No. 457,145, issued Aug. 4, 1891 to H. L. Bridgman, disclosed as an ore sampling machine that divides a mass into two or more portions and has the capability to further divide the divided portions into further divisions, But, this machine is not applicable for use with extracting a sample from an open container such as a truck. Further, U.S. Pat. No. 523,731 issued July 31, 1894 to G. D. Potter, discloses ore sampling machinary which extracts a sample from the discharge end of a chain-type conveyor via a pivotal chute, and like the machine disclosed in U.S. Pat. No. 457,145 is not applicable for use in extracting samples from open container carriers, and the like.
U.S. Pat. No. 1,105,702, issued Aug. 4, 1914 to T. J. Sturtevant, discloses a crushing mill which includes an arrangement for dividing a crushed sample of a product, and this device suffers from the deficiencies of those patents discussed above as regards application to extracting samples from open container carriers. In a like manner, the coal sampling machine shown in U.S. Pat. No. 1,186,646, issued June 13, 1916 to L. L. Beeken, is constructed only for use in extracting a sample from a moving stream of a product being analyzed.
U.S. Pat. No. 1,591,092, issued July 6, 1926 to A. G. McGregor discloses a sampling apparatus which permits the percentage of a sample to be varied from time to time, but like the references discussed above is applicable only to extracting a sample from a moving stream of material.
U.S. Pat. No. 3,841,161, issued Oct. 15, 1974 to F. R. Huntington discloses an overhead, extensible sampling device wherein an auger is reciprocally disposed within a tubular casing so as to permit the auger to be extended from the casing and into a load of bulk solid disposed in a hopper car, on a conveyor belt, and the like.